Recently, in addition to an increase in a popularization of portable electronic devices such as a notebook computer and a personal portable communication device, a market size of digital appliances and personal computers is constantly increased. Display apparatuses which are final connection medium between such devices and users is required to have a light weight and low power consumption. Therefore, FPDs (Flat Panel Displays) such as an LCD (Liquid Crystal Display), a PDP (Plasma Display Panel) and an OELD (Organic Electro-Luminescence Display) are generally used instead of a conventional CRT (Cathode Ray Tube).
As described above, in case of generalized FPD system, a timing controller, a scan controller and a data driver are required for driving a panel that is used for actual display. However, a large amount of an EMI (electromagnetic interference) and an RFI (radio frequency interference) hereinafter commonly referred to as “EMI”) are generated in a line for transmitting a data signal between the timing controller and the data driver.
Moreover, in case of current FPD system, a large screen and a high resolution are constantly pursued, and in case of a high resolution panel in particular, since the number of a data line runs from few hundreds to few thousands, an input to the data driver for driving each of the data lines requires a high speed data transmission technology.
As described above, since an EMI standard is reinforced recently, and a technology for transmitting a signal in a high speed is far more required, a small signal differential signaling scheme such as an RSDS (Reduced Swing Differential Signaling) or a mini-LVDS is commonly used in an intra-panel display for connecting the timing controller and the data driver accordingly.
FIG. 1 is a schematic diagram illustrating an embodiment of a conventional RSDS(Reduced Swing Differential Signaling), and FIG. 2 is a schematic diagram illustrating an embodiment of a conventional mini-LVDS (Low Voltage Differential Signaling). The RSDS and mini-LVDS both comprise one or more data signal lines to meet a required bandwidth using a separate clock signal synchronized to a data signal. Since only one clock signal is used, the clock signal and the data signals must be provided to match the number of data drivers 20 and 21 inside the panel. That is, as shown in FIGS. 1 and 2, the RSDS and the mini-LVDS both employ a multi-drop method.
However, the multi-drop method employed by both the RSDS and the mini-LVDS is disadvantageous in that a maximum operating speed limited due to a large load of the clock signal as well as an increase in EMI and degradation of quality of the signal such as a signal distortion due to impedance mismatch at a point where lines are split.
An intra-panel interface employing a point-to-point scheme recently announced by National Semiconductor Corporation is a PPDS (Point-to-Point Differential Signaling). In accordance with this method shown in FIG. 3, clock signals are transmitted to each of data drivers 22 to solve a problem that occurs when the clock signal is shared by the data driver 22. Moreover, this method is characterized in that an independent data line is disposed a timing controller and a single data driver 22 while a plurality of data lines are connected to a plurality of data drivers conventionally. That is, as shown in FIG. 3, in case of the PPDS, a serial method is employed to a single independent data line is disposed from a PPDS timing controller 12 toward the single data driver 22.
Therefore, the impedance mismatch is reduced compared to the conventional multi-drop method employed by the RSDS and the mini-LVDS so that EMI is reduced and a low manufacturing cost is achieved by reducing the number of total signal line.